Synthesis and reactions of 12-aryl-1,2,3,4-tetrahydro-6H-indazolo-[2,1-a]benzotriazolium hydroxide inner salts and 8,9,10,11-tetrahydro-7,10,10-trimethyl-8-oxo-5H-indazolo[1,2-a]benzotriazolium hydroxide inner salt

Abstract

Reductive deoxygenation of 3-aryl-4,5,6,7-tetrahydro-2-(o-nitrophenyl)indazoles in triethyl phosphite gave the corresponding triazapentalenes (II). The analogous reaction of 6,7-dihydro-3,6,6-trimethyl-1-(o-nitrophenyl)-indazol-4(5H)-one yielded the trimethyltriazapentalenone (VII). These compounds did not undergo ready electrophilic substitution. 3-[1-Methyl-2-(o-nitrobenzylidene)hydrazino]cyclohex-2-enone (IX) in triethyl phosphite gave 3-[N-methyl(indazol-2-yl)amino]cyclohex-2-enone (XII).